1. Field of the Invention
The present invention relates to a radio apparatus and a data reproducing method.
2. Description of the Related Art
Conventionally, the received signal modulated by the frequency modulation system such as the 4 level FSK (Frequency Shift Keying) includes a synchronization word (Frame-Sync-Word) for the synchronization at the receiver side. After the frame synchronization using the synchronization word included in the received signal, the receiver demodulates the received signal.
For example, Japanese Patent Application Laid-open No. 6-85865 discloses the art in which the received data is stored in advance and, after the synchronization is established, the DC offset is cancelled from the stored received data. Further, Japanese Patent Application Laid-open No. 8-23328 discloses the art in which the data of a predetermined number of bits before and after the normal anterior half part data position is obtained after the synchronization word is detected; and out of the obtained data, the data in the position that corresponds to the bit displacement detected at the time of the detection of the synchronization word is reproduced as the anterior half part data.
However, when the received signal has the frame structure in which the anterior half part data and the posterior half part data are separated interposing the synchronization word, it is necessary, in the synchronization detection at the time of the initial synchronization, to include the detected wave data that is unnecessary for the reproduction of the anterior half part data to perform the symbol detection, in order to prevent the clipping off of the beginning of the data reproduction due to the anterior half part data being unable to be demodulated. Therefore, unnecessary process is caused resulting in longer data reproduction time, and there is a problem that some systems require to wait for a few frames in order to ensure the next anterior half part data.